Mica Dam Embankment Stress Analysis

Mica Dam, the world's highest embankment dam, was constructed of excellent fill materials, that were heavily compacted. There is evidence that very low total stresses exist in the core, at some places not greater than 25% of the overburden pressures. The low core stresses are believed to be a result of arching of the more compressible till core to the very stiff granular shells. Stresses were computed from a two- dimensional plane strain finite element analysis of a longitudinal section of the dam, using material parameters derived from settlement observations in the dam. Low construction pore pressure cells tend to confirm the low total stresses. Water inflow tests were carried out in movement gages in the core, and the results suggest that the total stresses are low enough for hydraulic fracturing to have been initiated in the lower regions of the dam core when the water level in the gages was raised to just about midheight.